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Gorby

Experiments using real soil for dioramas (+ static grass)

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I have an excellent diorama book that suggests using real soil, but of course soil is organic (as in 'containing living matter' rather than the veg that's twice the price in Waitrose) so to answer the following questions, I did a few experiments.

 

Would it help to heat/cook it first?

It is better to sprinkle the soil onto a bed of PVA, or mix it with PVA and apply it as a paste?

Would there be a problem using static grass with it?

 

I received some excellent suggestions from other BM members that managed to push me in the right direction, then I went digging in the garden. After removing the larger stones, planty bits etc. it got portioned out into foil takeaway containers. After suffering the slings and arrows of outrageous sarcasm from the females of the house, I loaded up the cooker.

 

Recipe for cooking garden:

Pre heat the oven to 200 degrees (gas mark – how should I know!). Cook for 20 minutes, then leave to cool before tasting.

 

The cooking kills any bacteria and other micro-whatsits so I'm not sure if this is suitable for the Buddhists amongst you. It also dries the soil to make it much easier to sieve.

At this point I remembered that I don't have a sieve and I didn't want to use anything that was also used for food (can you imagine the ear-ache? :blah:). I immediately had to ignore the thoughts that Mrs Gorby's cocktail shaker would be perfect, as the result would be a lot more messy for me than the shaker. After a look around and straining the think muscles, I used my wire paintbrush holder for the initial thinning down, using the handle of a small hammer to grind the soil through the holes.

Please note: this is a very, very messy process and produces a LOT of soil dust. Doing it by my airbrush wasn't one of my best ideas.

939cb0c2-dcb9-457b-a1b3-5e49af1023bb.JPG

 

Then I used a large tea infuser (which is too big to go in our current teapot) to sieve it to it's final state. Even more dust!

0663a244-124c-436d-ab77-34017b884d45.JPG

 

On the left is the soil after the first sieving, and the final stuff on the right.

4950241b-d3f3-40ae-9cf8-ab6b86a3da5a.JPG

 

Using a suitable board (with the surface sanded to provide a key) I spread some slightly thinned PVA (to save me having to say it every time, when I mention PVA, it's 'slightly thinned with water') and using the tea infuser, scattered copious amounts of soil.

dbf205cf-d472-40e4-bc8d-a783f99b8727.JPG

 

When it dried, the thickness of the soil was patchy and too thin, so I used spray adhesive over the top and scattered more soil. This is the 'before':

f702e3e7-574c-4b65-94a2-92396ccab42b.JPG

 

Note: don't use spray adhesive.

The surface began to bubble excessively.

17bbf4e1-7e8e-427e-b11a-3faff6dadfa4.JPG

 

I had to puncture all the bubbles and then roll the surface flat. But at least the soil thickness was acceptable now. If you need to add more soil, wait for the first bit to dry, then use a brush to spread the PVA over the top.

 

Next experiment: I mixed soil with some PVA, making sure that there was quite a high ratio of soil to PVA, then spread it on the surface of the board with an old scrapper (quite a satisfy process) trying to make it look as natural as I could.

c2714abe-66c2-48f9-bb4a-c3836cf7e0e7.JPG

 

After a couple of hours this is the result. As you can see the sprinkled soil is much lighter – more like the soil in the garden. The mixed and spread soil is significantly darker – more like mud.... but…

2d0777cc-2428-4ffa-8e88-b82cca62d4a3.JPG

 

After drying for 24 hours it lightened significantly, so it is possible that it will eventually match the sprinkled soil.

29cd0516-3c5a-4f3a-9a6b-23c386ece987.JPG

 

Next experiment: Static grass.

Please ignore the awful colour of the 'grass', that's why I'm using it for these tests.

Spreading some PVA onto half the previous samples and the area between using a two inch brush, I applied the grass in the usual way. Then immediately turned the board over and whacked the loose grass off and tided the excess away, as quick as I could. Then using the tea infuser, I sprinkled more soil over the grass. Then left it to dry. Previously when I've done static grass, the end result looks a bit…. Ereerm…. A bit balding and just false, so I hoped that sprinkling the soil would make it a little more natural looking. That was the point of the, previously empty, centre section of my test piece. It definitely looks better with the sprinkled soil.  

 

Conclusion:

If you want the surface to be as flat as a bowling green, then apply the grass onto the bare board and sprinkle soil when the PVA is still wet.

7df0b912-0391-477c-af0f-b4814df66654.JPG

 

If you want the surface to be reasonably flat, but a little more natural looking, apply the grass over the soil sprinkled on the PVA, and then sprinkle more soil over the grass.

ca4a75e7-4200-42ad-a953-292452ee1678.JPG

 

If you want a more control over the ruggedness of the surface, mix the soil with PVA and spread it on the surface before doing the grass and soil sprinkle thing.

754779fc-13e7-46a3-bdbd-611fe4a75c06.JPG

 

Final experiment: Changing the colour of the soil (making mud pies).

I mixed some Tamiya gloss black (X-1) with the PVA to see if I could make mud.

I can't remember where I heard or read it, but someone said that mud isn't glossy, but when I look at mud, it looks glossy to me. Even though I used gloss paint, the soil/PVA mix dried quite matt, so I sprayed half with gloss to compare the effect.

afa28794-33c5-4cb3-ac88-68a134715c38.JPG

 

Personally I think the glossed area looks more like wet mud.

 

**************************************************************************************************

 

Further dirty adventures…

 

@dcrfan mentioned that if the soil is too finely sieved, it lacks the character of real soil. A very good point which leads me to another experiment.

The rejected stuff from the first sieving was discarded as the bits were quite big (certainty in 1/48 scale), but the stuff that didn't make the grade on the second sieving, I kept in case it would come in useful.

 

I spread a very generous amount of PVA and scattered an even more generous amount of the coarser stuff and the fine soil mixed together, then quite gently pressed it into the PVA with the side of hand to bed it into the glue. It was left for about half an hour before I shook off the excess. To my eyes this was an immediate improvement over the smooth soil. Would the difference in texture be completely hidden buy static grass though? Keep tuned.

ddfed6bb-6c91-4ccc-a020-956687e466c6.JPG

 

1d29df93-1954-4dea-be97-6e11286420a7.JPG

 

Part two:

Some of the coarser stuff and the fine soil was mixed together and then mixed with PVA to make a muddy paste. But the process of troweling it onto the surface, pushed the gritter bits below the surface hiding them completely. So I had to resort to scattering the coarser bits over the surface and lightly pressing them part way in. I pressed them in because stones aren't always on the surface of soil, they usually seem to be partly buried. I'm not so sure that this looks as natural as the soil that was scattered on PVA, but it still looks better then the smooth stuff in my opinion, so thanks Dcrfan.

c24508a7-32d5-44c9-abe4-69dff50bf47f.JPG

The colour is uneven because it has only had 24 hours to dry.

8b01a61a-5704-460a-bce3-53ed157f6db5.JPG

 

On my planned diorama I would like to do an smallish earth embankment (about 1/48 chest height) so I troweled the stuff on reasonably thick (about 4 to 5mm) and as you can see, it has cracked quite badly as it has dried, so I'm either going to have to use lots of shallower layers or use something underneath, with just a thinnish layer of soil on the top.

 

Static grass:

Putting static grass over the top completely hides the 'improvements' to the soil. I scattered some coarse soil over the grass while the PVA was still wet, but most of the lumpy bits fell off (maybe not enough PVA). Just sprinkling a few coarse bits over the grass did improve it a bit, but obviously they are loose. Having said that, the completed dio is unlikely to be turned on its side or upside down, so if it's kept level, the grass should do quite a good job of keeping the gritty bits in place. The photos below is before the gritty bits were added.

3eef6db7-d2d2-49b7-873e-96821dc2054d.JPG

 

06a5b0a1-9ce1-4dd8-987c-b8c85820bc1c.JPG

 

If anyone has any ideas for improvements or further experiments I'd be very interested

 

Thanks for looking and I hope this has helped. I'd be interested to hear your views or comments.

 

Gorby

 

Edited by Gorby
addition

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Thanks for posting this, it was very informative. I've been collecting bits to do some yet to be determined WWII airfield scene, and this will be useful.

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8 minutes ago, dnl42 said:

WWII airfield scene

That is what mine is intended for as well.

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Could you try putting down the soil and then using one of those plant watering misting sprays to mist a thinned down a PVA mixture with a bit of washing up liquid to break the surface tension.  Mist over the surface not at it then let the glue soak into the soil.

 

 

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12 hours ago, Grey Beema said:

Could you try putting down the soil and then using one of those plant watering misting sprays to mist a thinned down a PVA mixture with a bit of washing up liquid to break the surface tension.  Mist over the surface not at it then let the glue soak into the soil.

 

 

That is a possibility, but because the soil is so fine and powder-like, the odds are that some of it will just blow away from where you need it, or off the dio base completely. Or I could be wrong – give it a go (I haven't got one of those misting spray bottles so I can't) this is the very definition of 'dirt cheap'.

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"Thanks for posting this, it was very informative. I've been collecting bits to do some yet to be determined WWII airfield scene, and this will be useful."

 

Here is my intended location and I will indeed want some variation . .  .

 

36878601452_a77d815658_z.jpg

 

thanks for showing the experiments

Ian

Edited by Mancunian airman

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4 hours ago, Mancunian airman said:

Here is my intended location and I will indeed want some variation . .  .

WOW! Looks like that going to be pretty spectacular. What scale is it?

 

Keep tuned as I will be trying something else out with the soil, when I get some time.

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Scale is 4mm to the foot

Currently 12' X 16' as seen in the photo, with another  8'x4' planned extension to the right giving an overall size of 12' X 20'. The T2 hangar at the back alone occupies a single 4' x 8' board. 🙂

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It just might be where I live but often dried earth looks almost Sandy like.  I am trying to consider that although the station may be about 3 years old there would have still been piles of earth that was either left over from construction of recent builds, the grass seed didn't take too well  . . .  OR, airmen have created footpath walkway across the grass area(s) . . .

 

A variation in the grass may well help in my case .....

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27 minutes ago, Mancunian airman said:

It just might be where I live but often dried earth looks almost Sandy like.  I am trying to consider that although the station may be about 3 years old there would have still been piles of earth that was either left over from construction of recent builds, the grass seed didn't take too well  . . .  OR, airmen have created footpath walkway across the grass area(s) . . .

A variation in the grass may well help in my case .....

This is very much what I'm giving some thought to as well for my airfield dio. Where the muddy areas would be from continual foot and vehicle traffic and were to put the sparsely grassed areas, it's getting a bit jumbled up in my head and my dio is significantly less complex than yours. 

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Hi Gorby,

with the comment you make in post 1, about the soil being thin in places.

If you look at photo's 4 & 5 the thinness to me looks to be where you 'missed' with the PVA.

Stop being mean and invest in a small (2") radiator roller, you'll get better coverage!

Thanks for taking the time and trouble to post this. 👍

Paul

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17 minutes ago, PhoenixII said:

Stop being mean and invest in a small (2") radiator roller,

If I stopped being mean, I'd stop being me and nobody wants that do they?

:tumble:

 

Hello?

Anybody?

:crying:


 

17 minutes ago, PhoenixII said:

looks to be where you 'missed' with the PVA.

I'd come to that conclusion myself. I originally spread the PVA with a scraper, but then decided that a 2” brush works a lot better.

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**** Please note that I've added more experiments to the end of the original post. ****

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Gorby, thanks for going the extra mile.

If anybody's doing a dried out reservoir, you've nailed it......:whistle:

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